jquery mousewheel

(function($) {
var toFix = ['wheel', 'mousewheel', 'DOMMouseScroll', 'MozMousePixelScroll'];
var toBind = 'onwheel' in document || document.documentMode >= 9 ? ['wheel'] : ['mousewheel', 'DomMouseScroll', 'MozMousePixelScroll'];
var lowestDelta, lowestDeltaXY;
if ($.event.fixHooks) {
for (var i = toFix.length; i;) {
$.event.fixHooks[toFix[--i]] = $.event.mouseHooks
}
}
$.event.special.mousewheel = {
setup: function() {
if (this.addEventListener) {
for (var i = toBind.length; i;) {
this.addEventListener(toBind[--i], handler, false)
}
} else {
this.onmousewheel = handler
}
},
teardown: function() {
if (this.removeEventListener) {
for (var i = toBind.length; i;) {
this.removeEventListener(toBind[--i], handler, false)
}
} else {
this.onmousewheel = null
}
}
};
$.fn.extend({
mousewheel: function(fn) {
return fn ? this.bind("mousewheel", fn) : this.trigger("mousewheel")
},
unmousewheel: function(fn) {
return this.unbind("mousewheel", fn)
}
});
function handler(event) {
var orgEvent = event || window.event,
args = [].slice.call(arguments, 1),
delta = 0,
deltaX = 0,
deltaY = 0,
absDelta = 0,
absDeltaXY = 0,
fn;
event = $.event.fix(orgEvent);
event.type = "mousewheel";
if (orgEvent.wheelDelta) {
delta = orgEvent.wheelDelta
}
if (orgEvent.detail) {
delta = orgEvent.detail * -1
}
if (orgEvent.deltaY) {
deltaY = orgEvent.deltaY * -1;
delta = deltaY
}
if (orgEvent.deltaX) {
deltaX = orgEvent.deltaX;
delta = deltaX * -1
}
if (orgEvent.wheelDeltaY !== undefined) {
deltaY = orgEvent.wheelDeltaY
}
if (orgEvent.wheelDeltaX !== undefined) {
deltaX = orgEvent.wheelDeltaX * -1
}
absDelta = Math.abs(delta);
if (!lowestDelta || absDelta < lowestDelta) {
lowestDelta = absDelta
}
absDeltaXY = Math.max(Math.abs(deltaY), Math.abs(deltaX));
if (!lowestDeltaXY || absDeltaXY < lowestDeltaXY) {
lowestDeltaXY = absDeltaXY
}
fn = delta > 0 ? 'floor': 'ceil';
delta = Math[fn](delta / lowestDelta);
deltaX = Math[fn](deltaX / lowestDeltaXY);
deltaY = Math[fn](deltaY / lowestDeltaXY);
args.unshift(event, delta, deltaX, deltaY);
return ($.event.dispatch || $.event.handle).apply(this, args)
}
}));